CMOS and CCD solid state imaging devices are well known as solid state imaging devices. The CMOS solid state imaging device is represented by a CMOS image sensor, and the CCD solid state imaging device is represented by a CCD image sensor. Two types of CMOS solid state imaging devices are known. One is a front side illumination type, and the other is a back side illumination type. In the front side illumination solid state imaging device, incident light is entered from a front surface of a semiconductor substrate. In the back side illumination solid state imaging device, incident light is entered from a back surface of a semiconductor substrate.
The back side illumination solid state imaging device enables high image quality and can increase the number of pixels, compared with the front side illumination solid state imaging device, and, thus, the former has been developed widely in recent years. JP 2005-268643-A discloses such a back side illumination solid state imaging device.
The back side illumination solid state imaging device shown in the patent publication is provided with micro lenses and a silicon substrate in which a photoelectric conversion portions are formed. The micro lenses condense incident light, and the condensed incident light is entered into the photoelectric conversion portions. The micro lenses are formed of an organic material and have a low refractive index. The silicon substrate has a high refractive index. Accordingly, when an incident light enters into the photoelectric conversion portions from the micro lenses, degradation of images arises due to interference of the incident light, and the transmission rate of the incident light is lowered.